Research News

The onset of vortex breakdown in supersonic flows remains an unsolved problem in physics. 

Associate Professor Toshihiko Hiejima discovered that a sufficient condition for spiral vortex breakdown to occur in supersonic flows can be derived from the conserved total enthalpy at the vortex axis under complete supersonic inflow conditions. The theoretical threshold was simply determined by the relationship between the magnitudes of the kinetic and internal energies (i.e. axial velocity squared and static temperature, respectively) downstream.

In addition, it was found that the squared velocity and static temperature in the sufficient condition were closely related to a rapid reduction in the helicity, which indicated that vortex breakdown occurred. Numerical simulations confirmed that the theoretical threshold corresponds to the onset of spiral vortex breakdowns in supersonic flows.

Paper information

Journal: Journal of Fluid Mechanics
Title: Onset of spiral vortex breakdown in supersonic flows
DOI: 10.1017/jfm.2026.11349
Authors: Toshihiko Hiejima
Published: 30 March 2026
URL: https://doi.org/10.1017/jfm.2026.11349

Contact

Toshihiko Hiejima
Graduate School of Engineering
Email: hiejima[at] omu.ac.jp

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